Compromised Blood Flow in the Optic Nerve Head after Systemic Administration of Aldosterone in Rats: A Possible Rat Model of Retinal Ganglion Cell Loss.

PURPOSE: To investigate the optic nerve head (ONH) blood flow, retinal vessel diameters, and retinal ganglion cell (RGC) loss after systemic administration of aldosterone in rats. METHODS: Aldosterone (80 µg/kg/day) or vehicle was administered using an osmotic minipump in Brown Norway rats. The mean blur rate in the vessel (MV) and tissue (MT) regions and retinal vessel diameters in the ONH were measured by laser speckle flowgraphy before and 1, 2, and 4 weeks after administration of aldosterone or vehicle. Intraocular pressure (IOP), blood pressure, and heart rate were recorded. The retrogradely labeled RGCs were counted in the retinal flatmounts prepared 5 weeks after treatment. RESULTS: The MV and MT in the aldosterone group significantly decreased at 2 and 4 weeks (MV: 2 weeks, p = 0.001, 4 weeks, p < 0.001; MT: 2 weeks, p = 0.02, 4 weeks, p = 0.03). The artery and vein diameters significantly decreased at 1, 2, and 4 weeks in the aldosterone group (all p < 0.001). The MV, MT, and vessel diameters remained unchanged in the vehicle group. Other parameters did not change over time in either group. RGC counts were significantly lower in the aldosterone group than in the vehicle group (p < 0.001). CONCLUSIONS: ONH blood flow decreased following retinal vessel constriction without changes in IOP or blood pressure in a possible rat model of RGC loss by systemic administration of aldosterone.

High sensitivity X-ray analysis for a low accelerating voltage scanning electron microscope using a transition edge sensor.

A scanning electron microscope transition edge sensor has been developed to analyze the minor or trace constituents contained in a bulk sample and small particles on the sample under a low accelerating voltage (typically <3 keV). The low accelerating voltage enables to improve the spatial analysis resolution because the primary electron diffusion length is limited around the sample surface. The characteristic points of our transition edge sensor are 1) high-energy resolution at 7.2 eV@Al-Kα, 2) continuous operation by using a cryogen-free dilution refrigerator and 3) improvement of transmission efficiency at B-Kα by using thin X-ray film windows between the sample and detector (about 30 times better than our previous system). Our system could achieve a stabilization of the peak shift at Nd-Mα (978 eV) within 1 eV during an operation time of 27 000 s. The detection limits with B-Kα for detection times 600 and 27 000 s were 0.27 and 0.038 wt%, respectively. We investigated the peak separation ability by measuring the peak intensity ratio between the major constitute (silicon) and the minor constitute (tungsten) because the Si-Kα line differs from the W-Mα line by only 35 eV and a small W-Mα peak superimposed on the tail of the large Si-Kα peak. The peak intensity ratio (I(W-Mα)/I(Si-Kα)) was adjusted by the W particle area ratio compared with the Si substrate area. The transition edge sensor could clearly separate the Si-Kα and W-Mα lines even under a peak intensity ratio of 0.01.

Effects of ripasudil, a rho kinase inhibitor, on blood flow in the optic nerve head of normal rats.

PURPOSE: To evaluate the effect of topically administrated ripasudil, a rho kinase inhibitor, on blood flow in the optic nerve head (ONH) of normal rats. METHODS: Ripasudil (0.4%) or placebo was administered in the right eye of normal Brown Norway rats in a double-blind manner. Laser speckle flowgraphy was measured in the ONH of the right eye 20 or 40 min after a single instillation and before and after 7 or 14 days of twice daily instillation. Mean blur rate was evaluated in the total area (MA), the vessel region (MV), and the tissue region (MT). Intraocular pressure (IOP), blood pressure, ocular perfusion pressure (OPP), and heart rate were also recorded at each time point. RESULTS: After a single instillation, MV was significantly larger at 40 min than 20 min in the ripasudil group (P = 0.044) and was significantly lower in the placebo group (P = 0.023). MA and MV 40 min after instillation were significantly larger in the ripasudil group than in the placebo group (P = 0.022 and P = 0.006, respectively). After continuous instillation, MA and MV in the ripasudil group significantly increased from baseline after 7 and 14 days of treatment (both P < 0.05) and MA, MV, and MT were significantly higher than in the placebo group (MA: 7 and 14 days, P < 0.01; MV: 7 days, P = 0.003, and 14 days, P = 0.012; MT: 7 days, P = 0.046). There were no significant changes in IOP, blood pressure, or OPP after single or continuous instillation. CONCLUSIONS: Topical instillation of ripasudil increased blood flow around the ONH in the eyes of normal rats.

Longitudinal Changes in Optic Nerve Head Blood Flow in Normal Rats Evaluated by Laser Speckle Flowgraphy.

PURPOSE: To investigate longitudinal changes in mean blur rate (MBR) measured by laser speckle flowgraphy (LSFG) in the rat optic nerve head (ONH), and the reproducibility of MBR. METHODS: Rats were dilated under general anesthesia. Intraocular pressure (IOP), blood pressure, ocular perfusion pressure (OPP), heart rate, and LSFG were measured 30 minutes later. Mean blur rate in the ONH was determined using LSFG-Micro and was subdivided into MBR of the total area (MA), vessel region (MV), and tissue region (MT). Mean blur rate measurements were repeated at 10, 11, 13, 19, and 20 weeks, then every 5 weeks until 60 weeks of age. Intrasession repeatability, intrasession reproducibility, and intersession reproducibility were evaluated. RESULTS: Coefficient of variation of MBR was 0.3 to 6.2%, 1.3 to 5.2%, and 5.8 to 30.4% for intrasession repeatability, intrasession reproducibility, and intersession reproducibility, respectively. Mean blur rate of the total area, MV, and MT increased similarly until 19 weeks of age, but stabilized thereafter until 60 weeks. Mean blur rate of the total area in the inferior quadrant was significantly higher than in the temporal quadrant from 19 to 55 weeks. These changes exceeded a range of corresponding coefficient of reproducibility. There were no significant changes in IOP, blood pressure, or OPP during the experimental period. CONCLUSIONS: Mean blur rate in the rat ONH changed over time, increased from 10 to 19 weeks of age, then stabilized until 60 weeks. Mean blur rate of the total area exhibited regional differences: higher in the inferior quadrant than in the temporal quadrant. Laser speckle flowgraphy-Micro may provide reliable information for evaluating longitudinal changes of rat ONH blood flow.

[A case of multiple sclerosis with bilateral intermediate uveitis].

We describe a case of 20-year-old woman with visual impairment in her left eye. Her left visual acuity was 0.07 and an ophthalmoscopic examination demonstrated bilateral intermediate uveitis (IU). A neurological examination on admission revealed lower nasal quadrantanopsia in her left eye and an exaggerated right patellar tendon reflex. A T2-weighted MRI showed multiple high-intensity lesions in the bilateral periventricular region, corpus callosum, medulla. A short T1 inversion recovery MRI also showed a swollen left retrobulbar optic nerve and posterior thoracic cord lesion at Th 9 level. The latter longitudinal length was approximately 20 mm. Laboratory investigation demonstrated no abnormalities including an anti-aquaporin-4 antibody. A cerebrospinal fluid examination revealed an increased IgG-index (1.21) with oligoclonal IgG babds. Initially, a diagnosis of retrobulbar optic neuritis with IU was made. She received subtenon corticosteroid injection with intravenous methylprednisolone pulse and oral prednisolone therapy. An immediate improvement of her visual symptoms and MRI abnormalities was observed. Approximately 1 year later, a new high-intensity lesion in the right internal capsule was present on a follow-up T2-weighted brain MRI, established a diagnosis of multiple sclerosis (MS) based on the McDonald criteria in 2010. Previous reports in Japan demonstrated few cases of uveitis in patients with MS and this is the first report of MS with IU in Japan.

Influenza virus-host interactome screen as a platform for antiviral drug development.

Host factors required for viral replication are ideal drug targets because they are less likely than viral proteins to mutate under drug-mediated selective pressure. Although genome-wide screens have identified host proteins involved in influenza virus replication, limited mechanistic understanding of how these factors affect influenza has hindered potential drug development. We conducted a systematic analysis to identify and validate host factors that associate with influenza virus proteins and affect viral replication. After identifying over 1,000 host factors that coimmunoprecipitate with specific viral proteins, we generated a network of virus-host protein interactions based on the stage of the viral life cycle affected upon host factor downregulation. Using compounds that inhibit these host factors, we validated several proteins, notably Golgi-specific brefeldin A-resistant guanine nucleotide exchange factor 1 (GBF1) and JAK1, as potential antiviral drug targets. Thus, virus-host interactome screens are powerful strategies to identify targetable host factors and guide antiviral drug development.

OCT evaluation of neuroprotective effects of tafluprost on retinal injury after intravitreal injection of endothelin-1 in the rat eye.

PURPOSE: To determine whether optical coherence tomography (OCT) is a useful technique to monitor retinal damage and to evaluate the neuroprotective effect of topical tafluprost in a rat model of intravitreal endothelin-1 (ET-1) injection. METHODS: A single intravitreal injection of ET-1 (0.2-200 pmol/eye) was performed in one eye. Optical coherence tomography imaging was performed until 2 weeks after ET-1 injection. Subsequently, an intravitreal injection of ET-1 (20 pmol/eye) was performed in one eye of each rat, which was followed by topical instillation of tafluprost or saline once daily for 4 weeks. Optical coherence tomography imaging was performed until 4 weeks after ET-1 injection. After the last OCT session, retinal ganglion cells (RGCs) were retrogradely labeled with Fluorogold. RESULTS: Endothelin-1 at doses of 20 to 200 pmol/eye caused a significant decrease in inner retinal thickness, whereas ET-1 at doses of 0.2 to 5 pmol/eye did not. The inner retinal thickness at 2 weeks postinjection was strongly correlated with Fluorogold-labeled RGC counts in the central retina (r = 0.92, P < 0.001). The inner retina of eyes treated with tafluprost was significantly thicker than eyes treated with saline at 1 and 2 weeks (P = 0.038 and P = 0.045, respectively). Fluorogold-labeled RGC counts in the central retina of eyes treated with tafluprost were significantly greater than in eyes treated with saline (P = 0.03). CONCLUSIONS: Optical coherence tomography is useful for monitoring inner retinal damage in a rat model of intravitreal ET-1 injection. Daily topical administration of tafluprost may be protective against ET-1-induced retinal injury in the rat.

[Use of the Pentax-AWS videolaryngoscope for bougie-assisted exchange of tracheal tubes].

A gum elastic bougie can be useful for tube exchange. One major problem with this technique is that it may not possible to pass a new tube over the bougie into the trachea, because the tip of the tube can collide with tissues around the glottis. We report a case in which tube exchange using the bougie was difficult, but the Pentax-AWS videolaryngoscope enabled tracheal intubation. In a 62-year-old trauma patient with head and neck stabilized using a Halo vest, was scheduled for emergency fixation of the neck. Exchange of a polyvinylchloride tube to a reinforced tube was planned. A bougie was passed through the old tube, removing the tube, and a new tube was advanced over the bougie, but it was impossible to advance the tube into the trachea. Insertion of a Macintosh laryngoscope did not enable intubation. The new tube was removed from the bougie, attached to the Pentax-AWS videolaryngoscope, and the tube (with the Pentax-AWS) was passed over the bougie. Although it was not possible to see the glottis with the Pentax-AWS, the tube was easily advanced over the bougie into the trachea. Operation went on uneventfully. We believe that, when it is difficult to advance a tracheal tube over a tube exchanger, the use of the Pentax-AWS may facilitate intubation.

In vivo quantitative evaluation of the rat retinal nerve fiber layer with optical coherence tomography.

PURPOSE: To determine whether optical coherence tomography (OCT) is useful for quantitative evaluation of the thickness of the rat retinal nerve fiber layer (RNFL) in an optic nerve crush model. METHODS: An OCT system was developed with a modified commercial time-domain OCT and a superluminescent diode with a bandwidth of 150 nm. Optical components were optimized to acquire rat retinal images. The right optic nerve was crushed intraorbitally with a clip. The left eye served as the untreated control. Circumpapillary OCT scans with a circle diameter of 500 microm centered on the optic disc were performed before and 1, 2, and 4 weeks after the crush. Repeatability and reproducibility of RNFL thickness measurements were evaluated. The RNFL thicknesses at 400, 500, and 600 microm from the center of the optic disc determined by linear vertical OCT scans were compared with thicknesses in retinal sections. RESULTS: The mean RNFL thicknesses in circumpapillary OCT scans were 27.9 +/- 1.8, 29.2 +/- 2.4, 19.9 +/- 2.3, and 4.5 +/- 3.6 microm before and 1, 2, and 4 weeks after the crush, respectively. RNFL thickness was unchanged 1 week after the crush, but then decreased significantly and progressively after the second week (P < 0.01). Coefficients of repeatability and reproducibility were less than 10% except for the crushed eyes at 4 weeks. RNFL thicknesses in OCT images correlated significantly with thicknesses determined histologically (r = 0.90, P < 0.001). CONCLUSIONS: OCT is a useful and valuable tool for quantitative evaluation of rat RNFL thickness.

[Use of the laryngeal mask airway prevents gas leak around a tracheal tube].

A 59-year-old man with cervical spondylosis was scheduled for a posterior spine surgery. After induction of anaesthesia with propofol and fentanyl, and neuromuscular blockade with vecuronium, the trachea was intubated using an 8.0-mm ID refinforced tube, without difficulty. After inflation of the cuff with 6 ml of air, there was no gas leak around the tube. The patient was placed in the prone position, and the head fixed to the operating table, using head pins. Several minutes later, there was a marked gas leak around the tracheal tube cuff. Addition of air to the cuff did not solve the problem, indicating rupture of the cuff. A size 5 laryngeal mask airway was inserted while the tracheal tube was left in place with the patient in the prone position. Inflation of the cuff of the laryngeal mask with 15 ml of air and occluding the connector part of the laryngeal mask prevented the gas leak, and adequate ventilation volume could be maintained afterwards. We believe that insertion of the laryngeal mask airway may be useful in minimizing gas leakage around a tracheal tube.

Awake tracheal intubation through the laryngeal mask in neonates with upper airway obstruction.

Neonates with Pierre Robin or Treacher-Collins syndrome are at risk of upper airway obstruction and may require surgical fixation of the tongue to the mandible. Such neonates are at high risk of hypoxia during induction of anesthesia and thus awake fiberoptic intubation would be required. We experienced neonates in whom awake fiberoptic intubation could not be carried out, because of severe hypoxia. Awake insertion of the laryngeal mask solved this problem. A 1-month-old neonate with Pierre Robin syndrome and another with Treacher-Collins syndrome were scheduled for surgical fixation of the tongue to the mandible, for constant upper airway obstruction. In both patients, awake fiberoptic intubation was attempted but abandoned, because SpO(2) rapidly decreased during the attempts. Awake insertion of the laryngeal mask relieved upper airway obstruction and facilitated oxygenation. Fiberoptic intubation through the laryngeal mask was easily achieved. Anesthesia was then induced. No hypoxia occurred after insertion of the laryngeal mask. In a further two neonates with Treacher-Collins syndrome and in one neonate with Pierre Robin syndrome, awake fiberoptic intubation through the laryngeal mask was also successful. We believe that in neonates with predicted difficult intubation, who are at risk of upper airway obstruction and awake fiberoptic intubation could aggregate hypoxia, awake insertion of the laryngeal mask can be useful in facilitating oxygenation (by relieving upper airway obstruction) and in facilitating fiberoptic intubation.

[NMDA receptor antagonist neurotoxicity and psychotomimetic activity].

Non-competitive NMDA receptor antagonists, in spite of their neuroprotective effects against neuronal ischemia, brain trauma, etc., cause neuronal damage in the rodent posterior cingulate and retrosplenial cortices (PC/RS), which are thought to be responsible brain regions for their psychotomimetic activity in humans. A number of anesthetics have not only GABAA receptor activating properties but also NMDA receptor antagonist properties. On the other hand, ketamine and nitrous oxide, both of which are potent non-competitive NMDA receptor antagonists and have little GABAA activating properties, are demonstrated to induce neuronal damage in the rat PC/RS. Furthermore, ketamine potentiates the neuronal damage by nitrous oxide. Although many anesthetics, such as halothane, isoflurane, barbiturates and benzodiazepines, inhibit the neuronal damage in the PC/RS by NMDA receptor antagonists, probably through GABAA receptor activation, we anesthesiologists should be aware of the risk of ketamine or nitrous oxide anesthesia, not to speak of the combined use of them, without using GABAA receptor activating agents.

Surgical treatment of limbal vernal keratoconjunctivitis by resection of a limbal lesion.

PURPOSE: To report our experience managing a limbal mass associated with limbal vernal keratoconjunctivitis (VKC) by surgical excision. METHODS: A 16-year-old girl was referred to our hospital with the chief complaints of itching and photophobia in both eyes. She had a 2-year history of gradually enlarging limbal gelatinous masses on the temporal limbus in both eyes, which were diagnosed as limbal papillae of VKC. As the symptoms in her left eye were more severe, surgical resection of the limbal mass in her left eye was performed to relieve mechanical stress on the eyelid, followed by a free conjunctival autograft taken from the supranasal bulbar conjunctiva. RESULTS: After excision of the mass, ocular inflammation and other symptoms gradually disappeared. At 12-month follow-up, there was no recurrence of the mass. Findings in a histological examination of the excised limbal lesion were consistent with those of limbal papilla of VKC. CONCLUSION: In recalcitrant cases of limbal VKC, in which the symptoms are apparently caused by an elevated limbal mass, surgical excision of the limbal mass can be one of the therapeutic modalities, and it may facilitate resolution of the symptoms caused by chronic limbal VKC.